VEETEBEAL COLILM X 79 



transverse diameter at the caudal part than the lamina- of the pre- 

 ceding vertebra. 



The spinous process is more slender and somewhat shorter, and its 

 inclination toward the tail is more marked. 



There are no distinct caudal articular processes. The caudal artic- 

 ular surfaces, which face ventrally and slightly laterally, are in the 

 ventral third of the maximum height of the vertebra, measured as 

 before. The neural canal is slightly smaller. 



The Thoracic Vertebra' from the fourth to the ninth, inclusive, are 

 similar, and it is difficult to distinguish them in a collection of ver- 

 tebras taken from different animals ; a strongly developed seventh, 

 for example, may be similar in size and in the prominence of its pro- 

 cesses to a sixth ; or a seventh which is less developed may resemble 

 an eighth. The difficulty is not great if we are studying the bones 

 of one animal. In this case it will be observed that, as we pass from 

 the third to the tenth, the following changes take place : 



The spinous processes decrease in length and increase in incli- 

 nation toward the tail. The transverse processes increase as to their 

 cephalo-caudal diameters. 



The median emargination in the cephalic border of the laminse 

 becomes narrower. 



The distance from the caudal articular surface to the tip of the 

 spinous process, measured on the perpendicular to the ventral surface 

 of the body, becomes gradually less, and the caudal articular surfaces 

 apparently rise from the ventral third of the line to its middle point. 



In the following description of the fourth, fifth, sixth, seventh, and 

 eighth vertebra?, characters are given which will enable the student to 

 recognize the vertebra? in anv normal skeleton : 



o 



The Fourth Thoracic Vertebra (Figs. 50, 51, 52) is almost identical 

 with the third. Two-thirds of its maximum height is dorsal to the 

 caudal articular surfaces. 



The spinous process is a little shorter. The caudal part of the 

 laminse is somewhat narrower. 



The lateral surface of the transverse process faces dorsally and 

 laterally, and in form is still oblong, with the long diameter oblique. 

 It is more convex and swollen, and its medial cephalic corner i> often 

 elevated into a decided tubercle. The cephalic surface of the trans- 



